WO1996032829A1

WO1996032829A1 - Compact transponder and method for making same

Info

Publication number: WO1996032829A1
Application number: PCT/CH1996/000110
Authority: WO
Inventors: François Droz
Original assignee: Em Microelectronic-Marin Sa
Priority date: 1995-04-12
Filing date: 1996-03-25
Publication date: 1996-10-17
Also published as: CN1186589A; DE69610697T2; AU4936996A; ATE197108T1; EP0820686B1; FR2733104A1; JPH11505604A; CA2217956A1; US5895235A; DE69610697D1; EP0820686A1; CN1097422C; TW290781B; AU704453B2; FR2733104B1

Abstract

A device (70), particularly a transponder, including an electronic assembly (34) and a coating consisting of a shell (20) defining a recess (66), and a solidified binder (64) in which the electronic assembly (34) is embedded. The housing (20) has an opening (26) originally used to insert the electronic assembly (34) and the binder (64) during the manufacture of the device (70). The outer surface (72) of the device (70) in the region of the opening (26) consists of the solidified binder (64). The above-described device is manufactured using a reservoir for filling the recess (66) with the binder (64) and recovering the excess binder, said excess binder and said reservoir being separated from the device once the binder (64) has at least partially solidified.

Description

SMALL SIZE ANSWERING DEVICE AND MANUFACTURING METHOD THEREOF

The present invention relates to a responder of small dimensions. We call responder (in English "transponder") an electronic module functioning as receiver - transmitter. Generally, a responder is arranged to provide an identification signal in response to a received excitation signal, which provides the energy necessary to enable the responder to generate the identification signal.

Several responders of small dimensions are known from the prior art. In document US Pat. No. 5,025,550, the transponder described is formed of a coil electrically connected to an electronic circuit, this assembly being disposed inside a glass casing completely enveloping the electronic assembly. In document US Pat. No. 5,235,326, there is also described a transponder formed by an electronic assembly comprising an integrated circuit connected to a coil, this assembly being situated inside a closed box integrally enveloping the electronic assembly. To ensure the stability of the electronic assembly, a binder is provided inside this box.

A similar device is also described in US Pat. No. 4,992,794 where the housing is closed by a plug. Such a solution is also proposed in the international patent application WO 92/15105. This latter document also proposes other embodiments for coating the electronic assembly of the answering machine. Provision is made in particular for a simple overmolding of the electronic assembly or for placing the electronic assembly between two sheets of heat-sealed plastic.

Finally, a responder of the same type is described in international patent application WO 92/22827. Various embodiments of the answering machine are proposed in this document. According to a particular embodiment (figure 4 of this document), it is planned to introduce the electronic assembly, formed of the coil electrically connected to an electronic circuit, inside a tube comprising in its upper part and inside this tube a ring made of fusible material. This ring is melted so as to close the opening for introducing the electronic assembly to form the responder.

All the transponders described above have a major drawback since the coating of the planned electronic assembly requires a relatively complex manufacturing process which increases the cost of the transponder.

In addition, in all the answering machines described in the various documents cited above, it is very difficult to ensure total filling of the external envelope defining a closed box integrally surrounding the electronic assembly provided inside this box .

The present invention proposes to overcome the drawbacks of the responders of the prior art described above. To this end, an object of the invention is to provide an electronic device, in particular an inexpensive answering machine in which the protection of the electronic assembly is perfectly ensured.

Another object of the present invention is to provide a method of manufacturing electronic devices, in particular answering machines, making it possible to manufacture them industrially for a low production cost.

The first object of the invention is therefore a device comprising an electronic assembly and a coating protecting this electronic assembly. This device is characterized in that the coating is formed by an external envelope, defining a pocket and having an opening, and a solidified binder completely filling the envelope and forming an external surface of the device in the region defined by said opening, l electronic assembly being embedded in the binder.

Thanks to the particular characteristics of the device according to the invention, the electronic assembly is properly protected by an open envelope, that is to say having an opening through which the electronic assembly and the binder could have been introduced, and by the filling binder in which the electronic assembly is embedded. Such a device differs from the prior art described above in that the external envelope is not entirely closed, which avoids at least one operation during the manufacturing process of this device. In addition, since the binder itself forms an external surface of the device, it is easy to ensure complete filling of the envelope, which makes the device compact and resistant. Then, the electronic assembly is completely coated with the binder, which ensures stable positioning and total protection. The invention also relates to a method of manufacturing an electronic device, characterized in that it comprises the following steps: supply of an envelope, defining a pocket, having an upper opening, - supply of a reservoir disposed above said envelope, this reservoir communicating with the pocket through the upper opening and having at least one filling opening, addition of a binder in liquid form to the reservoir, provision of an electronic assembly in the pocket through the 'upper opening provided in the envelope, complete filling of the bag with the binder, hardening of the binder provided, - separation of the electronic device, formed by the envelope and the electronic assembly embedded in the solidified binder, of the reservoir.

The method according to the invention described above has several advantages. In particular, the presence of the reservoir makes it possible to supply the binder in an amount greater than the binder necessary to form the electronic device according to the invention. This eliminates the delicate question of dosing the binder, while ensuring full filling of the pocket defined by the envelope of the electronic device.

In the case where the upper opening of the envelope is relatively small, the reservoir can act as a funnel thus allowing easy filling of the bag. This filling would require complex and expensive equipment without the presence of said tank. According to a particular embodiment of the invention, the reservoir came integrally with the envelope. As a result, the reservoir and the envelope initially provided form a single piece of the same material. In such a case, the final separation of the electronic device from the reservoir can be carried out by machining, for example by simple cutting, using a blade or using a laser beam, at the level of the upper opening of the envelope of the electronic device.

According to a preferred embodiment, it is planned to associate several envelopes with a common tank, each of these envelopes having an upper opening opening onto this common tank. Therefore, it is possible to fill several envelopes with a single supply of binder in the common tank. This step will advantageously be carried out by depositing a binder wire closing the openings of several envelopes.

Other characteristics and advantages of the invention will be better described with the aid of the following description, made with reference to the appended drawings in which: FIG. 1 schematically represents a longitudinal section of a first embodiment of a answering machine according to the invention; FIG. 2 represents a set of envelopes associated with a common reservoir for implementing the process for manufacturing responders according to the invention; FIG. 3 represents several electronic assemblies connected to a common support for said implementation of the method according to the invention, Figures 4 and 5 schematically represent, in a sectional representation, two successive states occurring during said implementation of the method according to the invention (the electronic assembly has not been cut); FIG. 6 represents a second embodiment of a responder obtained by the manufacturing method described using FIGS. 2 to 5.

In Figure 1 is shown a first embodiment of a responder according to the invention. In this figure 1, the responder 2 is shown in a longitudinal section. It comprises an electronic assembly 3 formed of an integrated circuit 4 electrically connected to a coil 6 wound around a core 8. The electronic assembly 3 is incorporated in a coating formed by a binder 10 in which it is embedded and by - an envelope 12 which defines an external wall of the responder 2.

According to the invention, it is provided that the envelope 12 does not fully envelop the electronic assembly 3. In fact, the envelope 12 has an opening 14 through which the electronic assembly 3 and the binder 10 have been introduced into this envelope. The envelope 12 thus defines an open pocket, entirely filled with the binder 10 and the electronic assembly 3. It will be noted that, according to the invention, an external surface 16 of the responder 2 is formed by the binder 10 itself. The casing 12 has an axis of revolution X-X and the external surface 16 can be flat, curved or slightly hollow.

During the manufacture of the responder 2, it will be ensured that the electronic assembly 3 is completely covered by the binder 10 in the region of the opening 14. If after filling of the envelope 12 with the binder 10 and after hardening of this binder, the part of the envelope 12 located in the region of the opening 14 is not completely and correctly filled by the binder 10, or if the surface 16 formed by the binder has bosses and irregularities forming sharp projections , it is possible to use a device used to smooth the external surfaces of such objects which is known of the skilled person. In professional parlance, we speak of a softening in the rotating barrel.

With the aid of FIGS. 2 to 5, a particularly advantageous embodiment of a method for manufacturing electronic devices according to the invention will be described below.

In the above-mentioned embodiment, provision is made to provide at least one envelope 20, defining a pocket, with an upper opening 26, and a reservoir 28 disposed above the envelope 20. The reservoir 28 comprises a lower hole corresponding to the upper opening 26 of the envelope 20. Then, the reservoir 28 is open in its upper part to allow the addition of a binder in this reservoir. It will be noted that, in a particularly advantageous manner, the reservoir 28 is associated with several envelopes 20, 20A, 20B and 20C each having an upper opening 26, 26A, 26B and 26C by which the pockets defined by these envelopes communicate with the common reservoir 28 Only four envelopes have been shown in FIG. 2, but this is in no way limiting. Indeed, it is without other possibility to provide a reservoir associated with any number of envelopes. By way of example, the diameter of the opening 26 is between two and three millimeters, while the main dimensions of the surface defined by the edge 30 of the upper opening of the reservoir 28 are greater, the width having approximately 5 at 6 mm and the length may reach several centimeters depending on the number of envelopes provided.

When the main dimensions of the opening 26 are relatively small, in particular less than 5 mm, the reservoir 28 also plays the role of a funnel for the binder provided. Indeed, the binder brought into the reservoir 28, during a step of the process described here, is formed by a viscous liquid. Given the viscosity of the binder provided, the drops deposited or the mass of binder deposited in the reservoir 28 have dimensions greater than the dimensions of the upper openings of the envelopes, in particular of the least main dimension of these openings.

When the openings 26, 26A, 26B and 26C are small, the binder, supplied in the form of a viscous liquid in the region defined by each of these openings, enters the pockets defined by the envelopes - 20, 20A, 20B and 20C . The reservoir 28 effectively functions as a binder reservoir during the interval of time necessary for filling said pockets.

Following what has just been mentioned above, it will therefore be noted that the reservoir 28 firstly acts as a reservoir for the binder provided in the form of viscous liquid and secondly as a funnel for filling the pockets defined by the envelopes provided with the reservoir 28. These two functions are particularly necessary and advantageous for the manufacture of electronic devices, in particular answering machines, of small dimensions.

It will be noted that the envelopes 20, 20A, 20B and 20C came integrally with the reservoir 28. The reservoir 28 and the envelopes 20, 20A, 20B and 20C therefore form a single piece of the same material. However, in an alternative embodiment, it is possible to provide that the reservoir 28 is physically separated from the envelopes provided.

In Figure 3 are shown several electronic assemblies 34, 3 A, 34B each formed by a substrate 36, 36A, 36B on which is arranged a coil 38, 38A, 38B wound on a core 40, 0A, 40B. Each coil is electrically connected to an integrated circuit 42, 42A and 42B. By way of example, each electronic assembly 34, 34A and 34B defines an electronic device for identifying people or objects.

All of the substrates 36, 36A and 36B are connected to a common support 44, which has positioning holes 46. The electronic assemblies 34, 34A and 34B are regularly arranged along the support 44, the distance 50 between two electronic sets off equal to the distance 48 separating two neighboring envelopes. Thus, according to the invention, it is planned to provide a plurality of electronic assemblies connected to a common support, the number of these electronic assemblies provided corresponding to the number of envelopes provided. Therefore, it is easily possible to simultaneously introduce the plurality of electronic assemblies into the plurality of corresponding envelopes. Thus, once the binder has been brought into the reservoir 28, the electronic assemblies are brought in and simultaneously introduced into the pockets defined by the envelopes at least partially filled with binder, as shown in FIG. 4. In this FIG. 4, the envelope 20 and the reservoir 28 are shown in section, the envelope 20 being cut longitudinally while the reservoir 28 is cut transversely.

Thereafter, reference is made to FIGS. 4 and 5 for the description of the mode of implementation of the method according to the invention described here.

A hole 54 is provided in the lower region of the envelope 20. In addition, the hole 54 opens onto an external recess 56 formed in the bottom 58 of the envelope 20. The hole 54 has an orifice function for the air escaping during the introduction of the binder into the envelope 20. The recess 56 is provided for recovering binder which can flow through the hole 54 during filling of the envelope 20. However, in order to limit the quantity of binder that can escape through the hole 54, it is provided, in an advantageous variant of the embodiment described here, to support the bottom 58 against a working surface 60 during the introduction of the electronic assembly 34, as shown in FIG. 4. By way of example, the surface 60 forms the upper surface of a silicone block 62. Thus, the binder 64 completely fills the envelope 20 during the introduction of the electronic assembly 34, as shown in FIG. 5.

Once the electronic assembly 34 is completely inserted into the pocket 56 defined by the envelope 20, a surplus of binder provided is collected by the reservoir 28. The reservoir 28 therefore has a third function, namely that of recovering a surplus of binder provided, which guarantees full filling of the bag 66 with the binder 64 without having to guarantee a very precise dosage when the binder is supplied.

Then, the binder 64 solidifies to form a compact mass in which the electronic assembly 34 is embedded. It will be noted that during the solidification phase of the binder 64, it is possible to keep the bottom 58 of the casing 28 in abutment the surface 60 of the block 62 or else to remove the block 62 since there is no longer any overpressure exerted on the binder 64, as is the case during the introduction of the electronic assembly 34 into the pocket 66. It will be noted that the overpressure effect generated by the introduction of the electronic assembly 34 into the pocket 66 is particularly present when the dimensions of the section of the coil introduced corresponds substantially to the dimensions of the upper opening 26 of envelope 20.

Once the electronic assembly 34 has been introduced into the pocket 66 and the binder 64 at least partially solidified, provision is made to separate the envelope 20, used to form the electronic device, from the reservoir 28. To do this, provision is made in the present mode of implementation a sectioning at the level of the cutting line YY. This sectioning can be carried out in various ways and for example using a blade or a heat source, such as a laser beam. During this sectioning, the substrate 36 of the electronic assembly 34 is separated from the support 44, which remains with the reservoir 28 and the residual binder 68. An electronic device is then obtained, in particular an answering machine 70, as shown in section in FIG. 6. The answering machine 70, defining a second embodiment of a device according to the invention, has an envelope 20 defining an external wall of this responder 70. Then, the envelope 20 forms an open pocket 66, this envelope 20 having an opening 26. The surface 72 of the responder 70 in the region of the opening 26 is formed by the solidified binder 64 in which is embedded electronic assembly 34.

It will be noted that the geometric shape of the section of the responder 70 can be arbitrary, the circular shape shown in FIG. 2 being in no way limiting.

It will also be noted that the envelope 20 is for example made of plastic and that the binder 64 is formed in particular by a two-component adhesive, for example an epoxy resin, an acrylic resin or also a polyurethane resin. In the case of an epoxy resin, the manufacturing process described above is carried out substantially at room temperature. A compact and full electronic device is thus obtained without having to resort to a hot coating technique which can be harmful for the printed circuit 42.

The reservoir provided in the method of manufacturing an electronic device according to the invention can have various different structures. It is in particular possible to provide for this reservoir to be formed by various cells defining respective funnels for the envelopes associated with this reservoir. According to a variant of the embodiment of the method described above, the reservoir is closed after the addition of the electronic assemblies so that an overpressure can be generated in the volume defined by the envelopes and the reservoir. It will be noted that the binder can, according to two variants, be provided before the tank is closed or after it by a filling opening allowing the binder to be brought under pressure. In the latter case, it it is in particular possible to provide for complete filling of the reservoir, the dimensions of which are reduced in order to limit the quantity of residual binder.

It should also be noted that the binder can generally be applied before or after the electronic assemblies.

According to another embodiment of the method according to the invention, provision is made to demold the solidified binder in the envelopes and the reservoir, in particular using the support 44 in a variant using elements similar to those shown in the figures 2 and 3, and then to separate the binder individually incorporating the electronic assemblies of the residual binder solidified in the reservoir. In this case, the device obtained has no external envelope. Finally, it will be noted that the method according to the invention is perfectly suited to the mass production of electronic devices in which the electronic assemblies are perfectly protected. However, the method according to the invention can without other be used for the part-by-part production of an electronic device. In this case, there is provided a reservoir specific to each envelope.

Claims

1. Device (2; 70) comprising an electronic assembly (3; 34) and a coating (10, 12; 20, 64) protecting this electronic assembly, characterized in that said coating is formed by an external envelope (12; 20 ), defining a pocket and having an opening, and a solidified binder completely filling said envelope and forming an external surface of said device in the region defined by said opening, said electronic assembly being embedded in said binder.

2. Device according to claim 1, characterized in that said envelope (20) has, in a region located at an end opposite to said opening, a hole (54) of small section.

3. Device according to claim 2, characterized in that said hole (54) opens onto an external recess (56) formed in said envelope.

4. Device according to one of the preceding claims, characterized in that said binder (10; 20) consists of an adhesive with two components.

5. Device according to one of the preceding claims, characterized in that said envelope (12; 20) is made of plastic.

6. Device according to one of the preceding claims constituting a responder, said electronic assembly (3; 34) comprising an integrated circuit (4; 42) electrically connected to a coil (6; 40).

7. A method of manufacturing a device (70) characterized in that it comprises the following steps: supply of an envelope (20), defining a pocket (66), having an upper opening (26); supply of a reservoir (28) disposed above said envelope, this reservoir communicating with said pocket through said upper opening and having at least one filling opening; - Providing a binder (64) in liquid form in said reservoir; bringing an electronic assembly (34) into said pocket through said upper opening; full filling of said pocket with said binder; - hardening of said site; separation of said device, formed by said envelope and said electronic assembly embedded in said solidified binder, from said reservoir.

8. Method according to claim 7, characterized in that the quantity of said binder (64) provided is greater than the quantity of this binder incorporated in said device (70) resulting after said separation step, this separation being effected by sectioning at level of said upper opening (26) of said envelope (20).

9. Method according to claim 8, characterized in that said reservoir (28) came integrally with said envelope (20), said reservoir and said envelope initially supplied forming a single piece of the same material.

10. Method according to one of claims 7 to 9, characterized in that said envelope (20) provided has a hole (54) in its lower part.

11. Method according to claim 10, characterized in that said hole (54) opens onto an external recess (56) arranged in said envelope (20).

12. Method according to claim 10 or 11, characterized in that said hole (54) is closed on the side external to said envelope (20) by closure means during the supply of said electronic assembly (34) dctns said pocket (66) formed by said envelope.

13. Method according to one of claims 7 to 12, characterized in that said reservoir (28) acts as a funnel for filling said pocket with said binder (64), the contour (30) of the opening of filling of said reservoir defining a surface whose two main dimensions are greater than at least the least dimension of the upper opening (26) of said envelope.

14. Method according to one of claims 7 to 13 wherein it is intended to simultaneously manufacture several devices, characterized in that several envelopes (20, 20A, 20B, 20C) are provided with a single common tank (28) communicating with the pockets, defined by said envelopes, by the upper openings (26, 26A, 26B, 26C) of these envelopes, several electronic assemblies (34, 34A, 34B) being brought and introduced respectively into said pockets.

15. The method of claim 14, characterized in that said electronic assemblies (34, 34A, 34B) are initially connected together by a support (44), these electronic assemblies being arranged under said support with a regular spacing (50) corresponding at the spacing (48) of said envelopes provided (20, 20A, 20B, 20C), said electronic assemblies being introduced simultaneously into said pockets using said support, this support being separated from these electronic assemblies during said separation step wherein the devices, formed respectively by said envelopes and said electronic assemblies embedded in said binder filling these envelopes, are separated from said common reservoir.

16. Device manufacturing method, characterized in that it comprises the following steps: contributions of several envelopes (20, 20A, 20B, 20C), defining pockets, having respective upper openings (26, 26A, 26B, 26C ); - Provision of a reservoir (28) disposed above said envelopes, this reservoir communicating with said pockets through said upper openings and having at least one filling opening; supplying a binder in liquid form to said reservoir; supply of several electronic assemblies (34, 34A, 34B) in said respective pockets by said upper openings, these electronic assemblies were connected together by a support (44); integral filling of said pockets with said liεuit, this binder at least partially filling said reservoir; hardening of said binder; separating said binder and said electronic assemblies from said reservoir and said envelopes; and separating said electronic assemblies, coated by said binder solidified in said envelopes, from said support and from said binder solidified in said reservoir.